Hadith 4:85
‘Abdallah b. ‘Amr reported God’s messenger as saying, ‘‘The gift to a believer is death.”( i.e. death is the means by which he gains an introduction to the delights of paradise.) Baihaqi transmitted it in Shu'ab al-iman .
وَعَن عبد الله بن عَمْرو قَالَ ك قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «تُحْفَةُ الْمُؤْمِنِ الْمَوْتُ» . رَوَاهُ الْبَيْهَقِيُّ فِي شُعَبِ الْإِيمَان
Original Reference: Mishkat al-Masabih 1609